The rate constant values for the decay of radioisotopes X and Y, used in radio-medicine, are 0.05 $$\text{h}^{-1}$$ and 0.025 $$\text{h}^{-1}$$ respectively. In a hospital, at a time $$t_0$$ the activity of a sample of X was found to be twice that of Y. The activities of the two radioisotopes will be approximately equal when the time elapsed is

A

twice the half-life of Y

B

twice the half-life of X

C

equal to the half-life of X

D

equal to half the half-life of Y